Deprotonation Equilibrium of 5-Tropolonediazonium Salt Strongly Favors 1,2,5-Tropoquinone-5-diazide Structure in Certain Solvents
作者:Ai Ito、Hideaki Muratake、Koichi Shudo
DOI:10.1021/jo400593r
日期:2013.6.7
5-Tropolonediazonium salt 1 is a well-known intermediate for the preparation of 5-substituted tropolone derivatives, but 1,2,5-tropoquinone-5-diazide 2, which is expected to be formed by deprotonation of 1, has not been reported. We synthesized 2, and the structures of 1 and 2 were investigated and compared. NMR and UV spectral data indicated that 1 is easily deprotonated in water, methanol, DMSO,
5-Tropolonediazonium盐1是制备5取代的Tropolone衍生物的众所周知的中间体,但尚未报道预期通过1的去质子化反应而形成的1,2,5-tropoquinone-5-diazide 2。。我们合成了2,并对1和2的结构进行了研究和比较。NMR和UV光谱数据表明1在水中,甲醇,DMSO和DMF中很容易去质子化,并且由于其强酸度(估计p K a)在这些溶剂中以2的形式存在(但在丙酮或乙腈中不存在)。-2.07)。因此,酸碱平衡显示出强烈的溶剂依赖性。化合物2可以作为卡宾前体合成得到。
Radical and Ionic Reactions of Indolizin-1-ols: Synthesis of 3-Arylsulfanyl-, 3-(Tropon-2-yl)- and 3-(Tropolon-5-ylazo)-1-hydroxyindolizines from 3,3-Difluorocyclopropenes
作者:Ilya V. Nechaev、Georgij V. Cherkaev
DOI:10.1021/acs.joc.1c00747
日期:2021.6.4
An aerobic multicomponent reaction between monoalkyl-3,3-difluorocyclopropenes, pyridines, and arylthiols has been discovered to afford 3-arylsulfanyl-1-hydroxyindolizines. This reaction proceeds via intermediate C3-free indolizin-1-ols, easily forming freeradicals in air. In the presence of arylthiols, potent radical traps, incorporation of arylsulfanyl substituent occurs at the C3 position of indolizin-1-ols